Vacuum cleaners of the aforementioned type have become established on the market. The basic design of these vacuum cleaners includes a base unit equipped with a carriage and an upper body pivotally connected to the base unit. During vacuuming, the upright can be flexibly maneuvered by pivoting and axially twisting the upper body. In a rest phase after completion or interruption of the vacuuming operation, the upper body can be moved to a vertical parked position, in which the main wheels on the base unit are at the same time pivoted rearward. In this manner, the footprint of the base unit is increased, allowing the upright to stand securely while not in use. German Patent Application DE 10 2007 040 954 A1 describes such an upright vacuum cleaner where the actuating mechanism for pivoting the main wheels to the parked position is made up of number of linked functional components. Among other things, an interposed gear mechanism is used here for the adjusting mechanism. While the actuating and adjusting mechanism proposed in this publication appears to properly perform the desired function, namely to move the main wheels to the parked position, the design and means chosen for this purpose appear to be complex and expensive. Moreover, a potential risk involved here is that the adjusting mechanism may be highly susceptible to failure due to the large number of individual components required and because of the use of a gear mechanism.